The development of anaerobic curing compositions based on a combination of certain acrylic-glycol esters with selected organic hydroperoxides as polymerization initiators has been described by Vernon K. Krieble in U.S. Pat. No. 2,895,950 and in numerous other United States patents since issued to the Loctite Corporation. As set forth in those patents, anaerobic curing is defined as the property of a polymerizable compound to polymerize rapidly and spontaneously to the solid state upon the exclusion of air or oxygen from the compound.
A particularly useful feature of such compositions is that, in addition to having anaerobic curing characteristics, the compositions have a long shelf life in the liquid state as long as contact with air is maintained. Compositions such as described above are found to be especially useful for joining adjacent surfaces of metal or glass, for fastening nuts on mating threads, for holding in place set-screws, tapered pins, wedges, clamps, shaft-hub assemblies, as well as for sealants in a wide variety of purposes.
Because of the growing commercial importance of anaerobic fastening and sealing technology, other polymerizable systems which would polymerize or cure under anaerobic conditions have been sought.